Tbh I really love the idea of, during the Orion Pax arc, Megatron just tells him "yeah you took the matrix but it completely warped you into someone else. It ruined our relationship, the other guy puppeting your body became my sworn enemy, and we've been fighting for like 4 million years". And Orion ofc remembers none of that but hates every bit of it.
And later, the autobots have to drag Orion back kicking and screaming and force the matrix back into him, because he DOES NOT WANT THAT SHIT!! That stupid old boomerang took all his memories and made him into a different person! He forgot all the love he had for his would-be mate! It made him turn his back on the oppressed people that actually needed him! It destroyed the life he and Megatronus were going to build together! No, no, NO! He's not going back and you can't make him! Fighting with all his strength to get away from them, struggling to hold his chassis closed, yelling as loud as he can for Megatronus to help him and not let them take him away a second time